Trade unionist Ms Gaviria Toro faced up to 40 years in jail on charges of "rebellion" and "serious conspiracy to commit a crime" and spent 27 months in a Colombian prison because of her involvement with an agricultural workers' union before her release last June.

Since January, the girls had been sending letters on her behalf to the Colombian Embassy in London, demanding her release.

"We first heard about Rosalba from our teacher Anne Piggott and we decided we wanted to do something to help her. So we made it our CSPE (Civic, Social and Political Education) project for the Junior Cert," Ellie said.

The girls set about writing a letter to the Colombian authorities and made 400 copies, getting the other students and their teachers to sign them. "We decided to send three a day for two to three months. We're good at pestering people," added Annie.

Ambassador Maruicio Rodriguez Munera began to take notice of the letters he was receiving from Kenmare on a daily basis and told his government in Colombia about them.

Ms Gaviria Toro heard about the girls' efforts in her cell at Villa Cristina women's prison in Quindio, Colombia, and wrote to them telling them: "I look forward to meeting you and thanking you in person."

"We never thought she actually meant she would come to Ireland but it's lovely," said Annie.

Ms Gaviria Toro spent four hours in school yesterday telling pupils about the struggles of the people in her country for justice and freedom.

Over 3,000 trade unionists are imprisoned in Colombia; 23 have been executed this year alone.